FontExceptions

FontExceptions are a feature in the Linux operating system that allows users to override font choices made by the system or a particular application. This feature is primarily used to handle differences in font rendering between various systems or to solve issues caused by font mismatches.

When an exception is made, the system or application will be forced to use the specified font, and will ignore any font settings set by the application. FontExceptions can be configured on a per-application or per-font basis, allowing for fine-grained control over font choices.

FontExceptions typically consist of a file containing a list of strings that specify the name of the application or system and the name of the font to use in that case. This file is usually read by the system's font rendering software during startup, and informs it of the overridden font choices. The file is typically placed in the system's font configuration directory, which varies per distribution.

The use of FontExceptions originated from the differences in font rendering between various systems. Some systems, like commercial Unix variants, rendered fonts differently from Unix-like systems, such as Linux. FontExceptions allowed Linux users to achieve a more uniform look and feel by overriding the font choices made by applications.

The feature has since been used to solve various issues related to font mismatches, and has seen widespread adoption among Linux distributions. Despite being a powerful tool for font control, FontExceptions are not extensively documented in most Linux distributions, and leading to confusion among some users.